The present invention relates to a method and an apparatus for controlling a vibrator. Particularly, the present invention relates to a method and an apparatus for controlling a pneumatic vibrator suited for actively suppressing vibrations from a vibration source such as a vehicle. And the present invention also relates to an electromagnetic vibrator controlling method and an electromagnetic vibrator suited for actively suppressing vibrations from a vibration source such as a vehicle.
One of such known pneumatic vibrators is shown as a damper in Japanese Patent Laid-open Publication (Heisei)11-230245 which comprises a mass member elastically supported by a mount attached to a vibrating object to be controlled, an air-tightly enclosed air chamber for changing its inner pressure to apply a vibrating force to the mass member, and a driving switch valve mounted across an air flow passage communicated with the air chamber for alternatively connecting to a negative pressure source and to the ambient pressure. The frequency and phase of vibration of the mass member can be controlled by operating the driving switch valve. As shown in FIG. 19, the air chamber of the damper 1 is communicated via the air flow passage 2 to the negative pressure source 3 such as an air intake port of an engine and the ambient pressure 4. When the switch valve 5 mounted across the air flow passage 2 switches between the negative pressure source 3 and the ambient pressure 4, the pressure in the air chamber can be varied to develop a desired level of vibrating force for vibrating the mass member. The switching action of the switch valve 5 for determining the vibrating force is controlled by changing the duty ratio of a control signal released from a driver 6. Such a conventional pneumatic vibrator is simple in the construction using not an electromagnetic driving means as a vibrating means in the damper and its advantages include smaller size, lighter weight, and lower power consumption.
However, the conventional pneumatic vibrator permits a change in the pressure in the air chamber determined by the switch valve 5 switching between the two different pressure sources 3 and 4 to generate not only a frequency component corresponding to the switching frequency but also a higher frequency component which may decline the effect of suppressing vibrations. For compensation, a silencer such as a branch hose 7 is provided across the air flow passage 2 between the air chamber and the switch valve 5 for reducing a change in the pneumatic pressure over a range of frequencies except the frequencies of vibration to be suppressed.
The silencer such as the branch hose 7 also attenuate a desired frequency component of the pneumatic pressure to be used together with the undesired higher frequency component, hence decreasing the vibrating force of the vibrator. FIG. 20 illustrates another conventional arrangement where a second electromagnetic valve 8 is provided across the air flow passage 2 for closing and opening the path between an air intake port 3 and a tank 3a arranged for stabilizing the negative pressure at the intake port 3. While the switching action of the first electromagnetic valve 5 is controlled by a pulse signal of a duty ratio tailored to minimize the higher frequency component and released from a driver 9, the closing and opening action of the second electromagnetic valve 8 is controlled by a signal of a duty ratio tailored to have an optimum level of the pneumatic pressure and released from the driver 9, thus suppressing the higher frequency component while eliminating the use of a branch hose. However, although the branch hose is eliminated, it is mandatory to provide the second electromagnetic valve 8 and the driver 9 in a combination and to control both the two electromagnetic valves 5 and 8 at a time with more difficulty. According, as the cost for controlling is increased, a resultant vibrator will hardly be priced down and be disadvantageous on the use in a vehicle or the like.
A further conventional electromagnetic vibrator is known as comprising an electromagnetic damper having a yoke with electromagnets mounted to a mount attached to a vibration source such as a vehicle chassis and a mass member elastically joined to the yoke by a rubber elastic member, and a drive controlling means for feeding the electromagnets with an electric control signal to produce a driving force corresponding to the magnitude of the electric control signal. This conventional vibrator drives the electromagnets to vibrate the mass member for generating a vibrating force which is used to actively suppress vibrations at the vibration source.
More specifically as shown in FIG. 21, the electric control signal C in the conventional vibrator is produced by having an input pulse signal S, e.g. an output of a rotary pulse sensor of which the frequency is correlated to the frequency of vibrations at the vibration source, synchronized and shifted by xcex8 in phase, and provided with a duty ratio favorably correlated with a level of the control amplitude to correspond to the amplitude of vibrations at the vibration source. As the mass member is vibrated by a driving means receiving the electric control signal C, the vibration develops a driving force to suppress the vibrations on a vehicle.
However, in the electromagnetic vibrator, the turning on and off of the electric control signal may produce and add a higher frequency component to the driving signal of a reference frequency provided for driving the electromagnets, hence inhibiting the mass member from applying a desired level of the vibrating force. FIG. 22 illustrates a conventional method of constructing the electric control signal C, which comprises producing a reference pulse signal P which is synchronized with an input pulse signal S and has such a duty ratio determined as to develop a minimum of higher frequency component, producing a carrier signal (not shown) of which the frequency is higher than that of a reference pulse signal P while substituting and correlating the control amplitude with the duty ratio to correspond to the amplitude of vibrations at the vibration source, and superimposing the carrier signal over the reference pulse signal P. Accordingly, the generation of a higher frequency component in addition to the reference frequency in the driving signal for driving the electromagnets can be attenuated by the reference pulse signal while the amplitude of the driving signal can be controlled by superimposing the carrier signal of which the duty ratio corresponds to the amplitude of vibrations at the vibration source.
However, when the duty ratio of the carrier signal component in the electric control signal C is lowered, it permits the current for driving the electromagnets to be declined due to the time constant of the electromagnets acting as an actuator in the electromagnetic driving means. This causes the relationship between the vibrating force for vibrating the mass member and the duty ratio of the carrier signal to be not linear with each other, hence failing to suppress the vibration to a desired level.
It is an object of the present invention to eliminate the above described problems and provide a vibrator controlling method and a vibrator for applying a desired level of the vibrating force while readily removing a high frequency component. It is another object of the present invention to provide a pneumatic vibrator controlling method and a pneumatic vibrator for applying a desired level of the vibrating force while removing a high frequency component at a low cost with the use of a simple arrangement having no silencer such as a branch hose provided across the air flow passage. It is another object of the present invention to provide an electromagnetic vibrator controlling method and an electromagnetic vibrator for applying a desired level of the vibrating force while readily removing a high frequency component.
For achievement of the above object, a method of controlling a vibrator which has a driving means equipped with an electric-to-mechanical converting mechanism for generating a driving force corresponding to the amplitude of an electric control signal received and a vibrating member driven for vibration by the driving force of the driving means, wherein the vibrating member is vibrated by the driving means fed with the electric control signal, which corresponds to the amplitude of vibrations at a vibration source, to generate a vibrating force for actively suppressing the vibrations at the vibration source, comprising the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; and producing the electric control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the electric control signal, produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal, to have the first spike increased greater in width than the other spikes.
According to the method of controlling a vibrator, as the electric control signal contains the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component, it can successfully inhibit the generation of the high frequency component in the driving means and develop a desired level of the vibrating force which contains a corresponding frequency component. Also, as the electric control signal contains the carrier signal of which the frequency is higher than that of the reference pulse signal and which is superimposed on the reference pulse signal while its control amplitude is correlated with and substituted by the duty ratio to correspond to the amplitude of the vibrations at the vibration source, it can favorably determine the vibrating force in response to vibrations of the vibrating member. Moreover, the first spike of each pulse of the electric control signal produced by superimposing pulses of the reference pulse signal on pulses of the carrier signal is greater in width than the other spikes in the same pulse. As the width of the first spike is greater than the width of each of the other spikes in the pulse, delay of the response of a driving current fed to the switching means to the reception of the electric control signal, which inhibits the vibrating force from corresponding to the duty ratio of the carrier signal when the duty ratio is lowered, can be avoided. More specifically, the vibrating member can be vibrated with the driving current which corresponds to the duty ratio of the carrier signal or is correlated with the amplitude of the vibrations at the vibration source. Since the vibrating member is vibrated to a desired level, it can develop the vibrating force optimum for actively suppressing the vibrations at the vibration source.
A method of controlling the vibrator according to the present invention is provided composing the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; and producing the electric control signal by providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source.
This controlling method allows the electric control signal to contain the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component so that it can successfully inhibit the generation of the high frequency component in the driving means and also develop a desired level of the vibrating force which contains a corresponding frequency component. Also, the electric control signal produced by providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal is used to control the switching action of the switching means, thus determining an optimum level of the vibrating force for the vibrations at the vibration source. Accordingly, the driving current determined by the electric control signal can successfully develop the vibrating force corresponding to the amplitude of the vibrations at the vibration source and attenuate the generation of the high frequency component at more effectiveness in addition to the effect of reducing the high frequency component derived from the reference pulse signal. As the vibrating force is determined to more precisely a desired level, it can actively suppress the vibrations at the vibration source.
A vibrator having a driving means equipped with an electric-to-mechanical converting mechanism for generating a driving force corresponding to the amplitude of an electric control signal received and a vibrating member driven for vibration by the driving force of the driving means, wherein the vibrating member is vibrated by the driving means fed with the electric control signal, which corresponds to the amplitude of vibrations at a vibration source, to generate a vibrating force for actively suppressing the vibrations at the vibration source, comprising: a reference pulse signal producing means for producing the reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; a carrier signal producing means for producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; and an electric control signal producing means for producing the electric control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the electric control signal, produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal, to have the first spike increased greater in width than the other spikes.
A further vibrator according to the present invention is provided comprising: a reference pulse signal producing means for producing a reference pulse signal having a given duty ratio and synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; a third electric control signal producing means for producing a electric control signal by providing at least one off intervals of a predetermined random timing and random width on each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source; a second storage means for mapping and storing a plurality of the control signals which have been produced by the reference signal producing means and the third electric control signal producing means from the input pulse signals correlated in the frequency with the vibrations at the vibration source; a second electric control signal read-out means responsive to the input pulse signal for reading its corresponding electric control signal out from the second storage means so that the electric control signal read out by the second electric control signal read-out means is applied to the driving means.
A method of controlling a pneumatic vibrator which has an air-tightly enclosed air chamber and a switching means provided across an air flow passage communicated to the air chamber for switching between two pneumatic pressure sources for supply of different pressures to communicate with the air chamber, wherein the air chamber is varied in the inner pressure by operating the switching means to produce a vibrating force for actively suppressing vibrations at a vibration source to be controlled, is provided comprising the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; and producing the control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the control signal, produced by superimposing pulses of the carrier signal on pulses of the reference signal, to have the first spike increased greater in width than the other spikes so that the switching action of the switching means can be controlled by the control signal.
According to the method of controlling a pneumatic vibrator of this invention, as the control signal contains the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component, it can successfully inhibit the generation of the high frequency component. Also, as the control signal contains the carrier signal of which the frequency is higher than that of the reference pulse signal and which is superimposed on the reference pulse signal while its control amplitude is correlated with and substituted by the duty ratio to correspond to the amplitude of the vibrations at the vibration source, it can favorably determine the vibrating force in response to a change in the inner pressure of the air chamber. Moreover, the first spike of each pulse of the control signal produced by superimposing pulses of the reference pulse signal on pulses of the carrier signal is greater in width than the other spikes in the same pulse. As the width of the first spike is greater than the width of each of the other spikes in the pulse, delay of the response of a driving current fed to the switching means to the reception of the control signal, which inhibits the vibrating force from corresponding to the duty ratio of the carrier signal when the duty ratio is lowered, can be avoided. More specifically, the switching means can be actuated with the driving current which corresponds to the duty ratio of the carrier signal or is correlated with the amplitude of the vibrations at the vibration source. Since the inner pressure in the air chamber is shifted to a desired level, it can develop the vibrating force optimum for actively suppressing the vibrations at the vibration source.
The method of controlling a pneumatic vibrator may be modified in which the first spike of each pulse of the control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes and correlated in width with the duty ratio of the carrier signal.
As the first spike of each pulse of the control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes of the same pulse, delay of the response of a driving current fed to the switching means to the reception of the control signal received in case of the duty ratio of the carrier signal lowered can be avoided, hence allowing the vibrating force to be generated corresponding to the carrier signal. Also, as the width of the first spike is not equal but increased corresponding to the duty ratio of the carrier signal, the driving current can favorably correspond to the duty ratio of the carrier signal. This allows the inner pressure in the air chamber to be varied corresponding to the amplitude of the vibrations at the vibration source. Accordingly, the vibrating force determined by the change in the inner pressure can be used to suppress the vibrations at the vibration source at higher effectiveness.
Alternatively, a method of controlling a pneumatic vibrator according to the present invention is provided comprising the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; and producing the control signal by providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source so that the switching action of the switching means can be controlled by the control signal.
This controlling method allows the control signal to contain the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component so that it can successfully inhibit the generation of the high frequency component. Also, the control signal produced by providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal is used to control the switching action of the switching means, thus determining an optimum level of the vibrating force for the change in the inner pressure of the air chamber. Accordingly, the driving current determined by the control signal can successfully develop the change in the inner pressure in the air chamber and thus a desired level of the vibrating force to actively suppress the vibrations at the vibration source.
The method of controlling a pneumatic vibrator may be modified in which as a plurality of the control signals have been produced in advance from the input pulse signals and stored in a map, one control signal corresponding to the current input pulse signal is selected from the stored control signals and used for controlling the switching action of the switching means.
This allows the generation of the high frequency component to be eliminated at the vibrating force determined by a change in the inner pressure of the air chamber and also, the driving current to be developed corresponding to the control signal. Accordingly, the inner pressure in the air chamber can be varied correlating with the amplitude of the vibrations at the vibration source. Moreover, the control signals are produced from the input pulse signals based on the vibration source and stored in a map. This can simplify the arrangement of the control section, thus significantly decreasing the cost of the controlling components.
A pneumatic vibrator according to the present invention is provided comprising: a reference pulse signal producing means for producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; a carrier signal producing means for producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; a control signal producing means for producing the control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the control signal, produced by superimposing pulses of the carrier signal on pulses of the reference signal, to have the first spike increased greater in width than the other spikes; and a switching control means responsive to the control signal produced by the control signal producing means for controlling the switching action of the switching means.
According to the pneumatic vibrator of the present invention, as the control signal contains the reference pulse signal produced by the reference pulse signal producing means, which is synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and has a duty ratio tailored to minimize the generation of a high frequency component, it can successfully inhibit the generation of the high frequency component. Also, as the control signal which contains the carrier signal of which the control amplitude is correlated with and substituted by the duty ratio to correspond to the amplitude of the vibrations at the vibration source is superimposed on the reference pulse signal is produced by the control signal producing means, it can favorably determine the vibrating force in response to a change in the inner pressure of the air chamber. Moreover, the first spike of each pulse of the control signal produced by the control signal producing means superimposing pulses of the reference pulse signal on pulses of the carrier signal is greater in width than the other spikes in the same pulse. As the width of the first spike is greater than the width of each of the other spikes in the pulse, delay of the response of a driving current fed to the switching means to the reception of the control signal, which inhibits the vibrating force from corresponding to the duty ratio of the carrier signal when the duty ratio is lowered, can be avoided. More specifically, the switching means can be actuated with the driving current which corresponds to the duty ratio of the carrier signal or is correlated with the amplitude of the vibrations at the vibration source. Since the inner pressure in the air chamber is shifted to a desired level, it can develop the vibrating force optimum for actively suppressing the vibrations at the vibration source.
The pneumatic vibrator may be modified in which the control signal producing means is replaced by a second control signal producing means for producing the control signal in which the first spike of each pulse of the control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes and correlated in width with the duty ratio of the carrier signal.
As the first spike of each pulse of the control signal produced by the second control signal producing means superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes of the same pulse, delay of the response of a driving current fed to the switching means to the reception of the control signal received in case of the duty ratio of the carrier signal lowered can be avoided, hence allowing the vibrating force to be generated corresponding to the carrier signal. Also, as the second control signal producing means modifies the width of the first spike to be not equal but increased corresponding to the duty ratio of the carrier signal, the driving current can favorably correspond to the duty ratio of the carrier signal. This allows the inner pressure in the air chamber to be varied corresponding to the amplitude of the vibrations at the vibration source. Accordingly, the vibrating force determined by the change in the inner pressure can be used to suppress the vibrations at the vibration source at higher effectiveness.
Alternatively, another pneumatic vibrator according to the present invention is provided comprising: a storage means for mapping and storing a plurality of the control signals produced in advance from the input pulse signals correlated in the frequency with the vibrations at the vibration source using the reference pulse signal producing means and the carrier signal producing means defined in claim 9 and the control signal producing means defined in claim 9 or the second control signal producing means defined in claim 10 a control signal read-out means responsive to the input pulse signal for reading its corresponding control signal out from the storage means; and a switching control means responsive to the control signal read out by the control signal read-out means for controlling the switching action of the switching means.
In this pneumatic apparatus, the control signals produced from the input pulse signals by the reference pulse signal producing means, the carrier signal producing means, and the control signal producing means or the second control signal producing means are mapped and saved in the storage means and when desired, one control signal corresponding to the input pulse signal is read out by the control signal read-out means and used for driving the switching means with the help of the controlling action of the switching control means. This allows the high frequency component to be successfully eliminated and the driving current to be generated corresponding to the control signal, hence developing a change in the inner pressure in the air chamber which properly corresponds to the control amplitude of the input pulse signal related to the amplitude of the vibrations at the vibration source. Also, since the control signals are mapped and stored in the storage means and when desired, one of them corresponding to the pulse signal from the vibration source is read out by the control signal read-out means, the control section can be simplified in the arrangement and thus reduced in the cost. Accordingly, the vibrating force of an optimum level can be generated to actively suppress the vibrations at the vibration source. In case of mass production, the vibrator can be fabricated at less cost particularly in the control section.
A further pneumatic vibrator according to the present invention is provided comprising: a reference pulse signal producing means for producing a reference pulse signal having a given duty ratio and synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; a third control signal producing means for producing a control signal by providing at least one off intervals of a predetermined random timing and random width on each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source; a second storage means for mapping and storing a plurality of the control signals which have been produced by the reference signal producing means and the third control signal producing means from the input pulse signals correlated in the frequency with the vibrations at the vibration source;a second control signal read-out means responsive to the input pulse signal for reading its corresponding control signal out from the second storage means; and a second switching control means responsive to the control signal read out from the second control signal read-out means for controlling the switching action of the switching means.
In this pneumatic vibrator, a plurality of the control signals produced in advance from the input pulse signals by the reference pulse signal producing means and the third control signal producing means are mapped and saved in the second storage means and when desired, one control signal corresponding to the input pulse signal is read out by the second control signal read-out means and used for driving the switching means with the help of the controlling action of the switching control means. More particularly, the reference pulse signal which is synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and has a duty ratio tailored to minimize the high frequency component can be generated by the reference signal producing means and eliminate the generation of the high frequency component derived from a change in the inner pressure in the air chamber. As the control signal is produced by the third control signal producing means providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal and used for controlling the switching action of the switching means, the vibration force can be determined to match the change in the inner pressure of the air chamber. Accordingly, the high frequency component can successfully be eliminated and the driving current can be obtained corresponding to the control signal. Hence, the inner pressure in the air chamber can favorably be varied to develop a desired level of the control amplitude corresponding to the amplitude of the vibrations at the vibration source.
Also, since the control signals are mapped and stored in the second storage means and when desired, one of them corresponding to the pulse signal from the vibration source is read out by the second control signal producing means, the control section can be simplified in the arrangement and thus reduced in the cost. Accordingly, the vibrating force of an optimum level can be generated to actively suppress the vibrations at the vibration source. In case of mass production, the vibrator can be fabricated at less cost particularly in the control section.
A method of controlling an electromagnetic vibrator, according to the present invention, which has a driving means equipped with an electric-to-mechanical converting mechanism for generating a driving force corresponding to the amplitude of an electric control signal received and a vibrating member driven for vibration by the driving force of the driving means, wherein the vibrating member is vibrated by the driving means fed with the electric control signal to generate a vibrating force for actively suppressing vibrations at a vibration source, is provided comprising the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; and producing the electric control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the electric control signal, produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal, to have the first spike increased greater in width than the other spikes.
According to the method of controlling an electromagnetic vibrator, as the electric control signal contains the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component, it can successfully inhibit the generation of the high frequency component in the driving means and develop a desired level of the vibrating force which contains a corresponding frequency component. Also, as the electric control signal contains the carrier signal of which the frequency is higher than that of the reference pulse signal and which is superimposed on the reference pulse signal while its control amplitude is correlated with and substituted by the duty ratio to correspond to the amplitude of the vibrations at the vibration source, it can favorably determine the vibrating force in response to vibrations of the vibrating member. Moreover, the first spike of each pulse of the electric control signal produced by superimposing pulses of the reference pulse signal on pulses of the carrier signal is greater in width than the other spikes in the same pulse. As the width of the first spike is greater than the width of each of the other spikes in the pulse, delay of the response of a driving current fed to the switching means to the reception of the electric control signal, which inhibits the vibrating force from corresponding to the duty ratio of the carrier signal when the duty ratio is lowered, can be avoided. More specifically, the vibrating member can be vibrated with the driving current which corresponds to the duty ratio of the carrier signal or is correlated with the amplitude of the vibrations at the vibration source. Since the vibrating member is vibrated to a desired level, it can develop the vibrating force optimum for actively suppressing the vibrations at the vibration source.
The method of controlling an electromagnetic vibrator may be modified in which the first spike of each pulse of the electric control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes and correlated in width with the duty ratio of the carrier signal.
As the first spike of each pulse of the electric control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes of the same pulse, delay of the response of a driving current fed to the switching means to the reception of the electric control signal received in case of the duty ratio of the carrier signal lowered can be avoided, hence allowing the vibrating force of the vibrating member to be generated corresponding to the carrier signal. Also, as the width of the first spike is not equal but increased corresponding to the duty ratio of the carrier signal, the driving current can favorably correspond to the duty ratio of the carrier signal. This allows the vibrating force to be adjusted to a desired level corresponding to the amplitude of the vibrations at the vibration source. Accordingly, the vibrating force of the desired level can be used to suppress the vibrations at the vibration source at higher effectiveness.
Alternatively, a method of controlling an electromagnetic vibrator according to the present invention is provided comprising the steps of: producing a reference pulse signal of a duty ratio synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; and producing the electric control signal by providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source.
This controlling method allows the electric control signal to contain the reference pulse signal synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and having a duty ratio tailored to minimize the generation of a high frequency component so that it can successfully inhibit the generation of the high frequency component in the driving means and also develop a desired level of the vibrating force which contains a corresponding frequency component. Also, the electric control signal produced by providing at least one of f intervals of a predetermined random timing and random width in each pulse of the reference pulse signal is used to control the switching action of the switching means, thus determining an optimum level of the vibrating force for the vibrations at the vibration source. Accordingly, the driving current determined by the electric control signal can successfully develop the vibrating force corresponding to the amplitude of the vibrations at the vibration source and attenuate the generation of the high frequency component at more effectiveness in addition to the effect of reducing the high frequency component derived from the reference pulse signal. As the vibrating force is determined to more precisely a desired level, it can actively suppress the vibrations at the vibration source.
The method of controlling an electromagnetic vibrator may be modified in which as a plurality of the electric control signals have been produced in advance from the input pulse signals and stored in a map, one electric control signal corresponding to the current input pulse signal is selected from the stored control signals and applied to the driving means.
This allows the generation of the high frequency component to be eliminated in the driving means and the vibration force to be adjusted to a desired for corresponding vibrations. Also, the driving current can be obtained corresponding to the electric control signal and thus the vibrating force can be applied corresponding to the amplitude of the vibrations at the vibration source. Moreover, the electric control signals are produced from the input pulse signals correlated in frequency with the vibrations at the vibration source and stored in a map. This can simplify the arrangement of the control section, thus contributing to the cost down of the control section of the electromagnetic vibrator.
An electromagnetic vibrator according to the present invention is provided comprising: a reference pulse signal producing means for producing a reference pulse signal of a duty ratio synchronized with an input pulse signal and correlated in the frequency with the vibrations at the vibration source; a carrier signal producing means for producing a carrier signal of which the frequency is higher than the frequency of the reference pulse signal while correlating and substituting the control amplitude with the duty ratio to correspond to the amplitude of the vibrations at the vibration source; and an electric control signal producing means for producing the electric control signal by superimposing the carrier signal on the reference pulse signal while allowing each pulse of the control signal, produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal, to have the first spike increased greater in width than the other spikes.
According to the electromagnetic vibrator of the present invention, as the electric control signal contains the reference pulse signal produced by the reference pulse signal producing means, which is synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and has a duty ratio tailored to minimize the generation of a high frequency component, it can successfully inhibit the generation of the high frequency component and develop a desired level of the vibrating force which contains a corresponding frequency component. Also, as the electric control signal which contains the carrier signal of which the control amplitude is correlated with and substituted by the duty ratio to correspond to the amplitude of the vibrations at the vibration source is superimposed on the reference pulse signal is produced by the electric control signal producing means, it can favorably determine the vibrating force. Moreover, the first spike of each pulse of the electric control signal produced by the electric control signal producing means superimposing pulses of the reference pulse signal on pulses of the carrier signal is greater in width than the other spikes in the same pulse. As the width of the first spike is greater than the width of each of the other spikes in the pulse, delay of the response of a driving current fed to the driving means to the reception of the electric control signal , which inhibits the vibrating force from corresponding to the duty ratio of the carrier signal when the duty ratio is lowered, can be avoided. More specifically, the vibrating member can be vibrated for developing a desired level of the vibrating force by the driving means fed with the driving current which corresponds to the duty ratio of the carrier signal or is correlated with the amplitude of the vibrations at the vibration source. This allows the electromagnetic vibrator to use a desired level of the vibrating force for actively suppressing the vibrations at the vibration source.
The electromagnetic vibrator may be modified in which the electric control signal producing means is replaced by a second electric control signal producing means for producing the electric control signal in which the first spike of each pulse of the electric control signal produced by superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes and correlated in width with the duty ratio of the carrier signal.
As the first spike of each pulse of the electric control signal produced by the second electric control signal producing means superimposing pulses of the carrier signal on pulses of the reference pulse signal is increased greater in width than the other spikes of the same pulse, delay of the response of a driving current fed to the driving means to the reception of the electric control signal received in case of the duty ratio of the carrier signal lowered can be avoided, hence allowing the vibrating force for vibrating the vibrating member to be generated corresponding to the carrier signal. Also, as the second electric control signal producing means modifies the width of the first spike to be not equal but increased corresponding to the duty ratio of the carrier signal, the driving current can favorably correspond to the duty ratio of the carrier signal, hence developing the vibrating force corresponding to the amplitude of the vibrations at the vibration source. Accordingly, the vibrating force of a desired level can be used to suppress actively the vibrations at the vibration source at higher effectiveness.
Alternatively, an electromagnetic vibrator according to the present invention is provided comprising: a storage means for mapping and storing a plurality of the electric control signals produced in advance from the input pulse signals correlated in the frequency with the vibrations at the vibration source using the reference pulse signal producing means and the carrier signal producing means defined in claim 17 and the electric control signal producing means defined in claim 17 or the second electric control signal producing means defined in claim 18 an electric control signal read-out means responsive to the input pulse signal for reading its corresponding electric control signal out from the storage means so that the electric control signal read out by the electric control signal read-out means can be applied to the driving means.
In this electromagnetic apparatus, the electric control signals produced in advance from the input pulse signals, each being correlated in frequency with the vibrations at the vibration source, by the reference pulse signal producing means, the carrier signal producing means, and the electric control signal producing means or the second electric control signal producing means are mapped and saved in the storage means and when desired, one electric control signal corresponding to the input pulse signal is read out by the electric control signal read-out means and used for driving the driving means. This allows, as defined in claims 17 and 18, the high frequency component in the driving means to be successfully eliminated thus to develop a desired level of the vibrating force which contains a corresponding frequency component and the driving current for the driving means to be generated corresponding to the electric control signal, hence using the vibrating force which properly corresponds to the amplitude of the vibrations at the vibration source. Also, since the electric control signals are mapped and stored in the storage means and when desired, one of them corresponding to the input pulse signal from the vibration source is read out by the electric control signal producing means, the control section can be simplified in the arrangement and thus reduced in the cost. Accordingly, the vibrating force of an optimum level can be generated to actively suppress the vibrations at the vibration source. In case of mass production, the electromagnetic vibrator can be fabricated at less cost particularly in the control section.
A further electromagnetic vibrator according to the present invention is provided comprising: a reference pulse signal producing means for producing a reference pulse signal having a given duty ratio and synchronized with an input pulse signal correlated in the frequency with the vibrations at the vibration source; a third electric control signal producing means for producing a electric control signal by providing at least one off intervals of a predetermined random timing and random width on each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source; a second storage means for mapping and storing a plurality of the control signals which have been produced by the reference signal producing means and the third electric control signal producing means from the input pulse signals correlated in the frequency with the vibrations at the vibration source; and a second electric control signal read-out means responsive to the input pulse signal for reading its corresponding electric control signal out from the second storage means so that the electric control signal read out by the second electric control signal read-out means can be applied to the driving means.
In this electromagnetic vibrator, the electric control signals produced from the input pulse signals, each being correlated in frequency with the vibrations at the vibration source, by the reference pulse signal producing means and the third control signal producing means are mapped and saved in the second storage means and when desired, one electric control signal corresponding to the input pulse signal is read out by the second electric control signal read-out means and used for driving the driving means. More particularly, the reference pulse signal of the electric control signal which is synchronized with the input pulse signal correlated in frequency with the vibrations at the vibration source and has a duty ratio tailored to minimize the high frequency component can be generated by the electric control signal producing means and used for eliminating the generation of the high frequency component in the driving means. As the electric control signal is produced by the third electric control signal producing means providing at least one off intervals of a predetermined random timing and random width in each pulse of the reference pulse signal to correlate the control amplitude with the amplitude of the vibrations at the vibration source and used for controlling the action of the driving means, the driving current can be obtained corresponding to the electric control signal and thus the vibrating force can be determined to match the amplitude of the vibrations at the vibration source. Accordingly, the generation of the high frequency component will be eliminated at more effectiveness in addition to the effect of the reference pulse signal for eliminating the high frequency component. Also, since the electric control signals are mapped and stored in the second storage means and when desired, one of them corresponding to the input signal can be read out by the second electric control signal read-out means, the control section can be simplified in the arrangement and thus reduced in the cost. Accordingly, the vibrating force of an optimum level in the electromagnetic vibrator can be generated to actively suppress the vibrations at the vibration source. In case of mass production, the electromagnetic vibrator can be fabricated at less cost particularly in the control section.